P1314: MONITORING OF CIRCULATING CELL FREE DNA IN HEMATOPOIETIC STEM CELL DONORS
Authors: Tatyana Rybolovleva, Ekaterina Tregubova, Elena Nazarova, Elena Poponina, Natalia Minaeva, Natalia Zorina
Journal: HemaSphere (2023)

Topic: 22. Stem cell transplantation - Clinical Background: Circulating cell free DNA (cfDNA) are short DNA fragments which are present in human plasma and other body fluids.In recent years, there has been an increased interest in research on cfDNA not only in patients with leukemias, but also in donors of hematopoietic stem cells (HSC). Transplantation of allogeneic HSC to patients is carried out after mobilization of HSC with granulocyte colony-stimulating growth factor (G-CSF) and collection of CD34+-cells from donors. Administration of G-CSF can lead to a change the cfDNA level in the blood serum. Aims: To evaluate the dynamic of the cfDNA level in HSC donors as a result of the stimulation of G-CSF and the correlation of the concentration of cfDNA with the number of mobilized HSC. Methods:The material for analysis was 142 of peripheral blood serum samples from 71 HSC donors aged 11 to 53 (median 33) years. Of these, 45 (63.4%) men and 26 (36.6%) women. The studies were performed before the G-CSF administration and on the day of the first cell apheresis (4-5 days after stimulation of the G-CSF). The isolation of serum cfDNA was performed on magnetic particles using the SileksMagNA-Direct kit (“Sileks”, Russia). The concentration of cfDNA (fragments 91 and 211 bp) was determined using the QuantumDNA kit for quantitative assessment of human DNA (“Evrogen”, Russia). The statistical significance of differences in cfDNA levels before and after the G-CSF administration was assessed using the Wilcoxon test. The difference in cfDNA concentrations was calculated by subtracting the values before the G-CSF administration and at the time of the first apheresis, after which the regression analysis was used to estimate the relationship of the resulting indicator to the number of mobilized HSC. The differences at p<0.05 were considered valid. Results:Before the G-CSF administration, the median concentration of the cfDNA 91 bp fragment was 0.20 (Q1-Q3: 0.10-0.35) ng/µl, on the first day HSC apheresis, the concentration increased to 1.00 (Q1-Q3: 0.58-1.62) ng/μl (p<0.001). The increase of cfDNA 91 bp fragments level was observed in 91.6% of donors (65/71). Comparison of the larger fragments (211 bp) of cfDNA concentration also revealed significant differences (p=0.011): before the G-CSF administration, the median content of these cfDNA fragments was 0.25 (Q1-Q3: 0.16-0.41) ng/μl, on the first day apheresis - 0.72 (Q1-Q3: 0.50-1.16) ng/µl. After stimulation, 76.2% of donors (16/21) showed an increase in 211 bp cfDNA containing. The average number of HSC received from donors at the first apheresis was 51.5 *109 CD34+-cells (95% CI 40.9-62.1). The regression analysis revealed a direct correlation of the difference in the level 211 bp cfDNA with a highest number of CD34+-cells prepared as a result of the first apheresis (rxy=0.744, p=0.001). Summary/Conclusion: The G-CSF administration to mobilize HSC in donors is accompanied by an increase in circulating cell free DNA levels. A direct correlationhas been established between the difference in the concentration of 211 bp fragments of cfDNA and an increase in the number of mobilized CD34+- cells. The impact of elevated levels of cfDNA on HSC donors requires further study. Keywords: Peripheral blood stem cell mobilization